HDBaseT® is a connectivity standard that enables the use of a single category cable to offer HD video, audio, Ethernet, controls, USB 2.0 and power. Transmission of data according to the HDBaseT® standard comes with several benefits that include time-sensitive transmissions, low delays and low latency. Legacy Ethernet networks are widely deployed, in both the consumer and industrial settings. Thus, it would be advantageous to utilize Ethernet networks to extend the scope of HDBaseT® networks. For example, this could extend HDBaseT® from in-room to cross-campus applications, and leverage existing pro-AV installations and interfaces to achieve end-to-end system optimization and reduced total cost of ownership.
However, HDBaseT® is based on a different protocol that basic Ethernet network equipment cannot work with. Thus, HDBaseT® data cannot be transmitted “as is” over a standard Ethernet/IP network. Therefore, there is a need to provide a way to transmit HDBaseT® data over a legacy Ethernet networks without requiring the networks to utilize non-standard equipment.
One challenge that needs to be addressed when transmitting data according to the HDBaseT® standard over an Ethernet network relates to the issue of synchronization of the different clock frequencies at various points in the network. In an HDBaseT® network, in which each of the points operates according to the HDBaseT® standard, each point in the network can measure the frequency offset from previous points in the network. Thus, the frequency offset between the endpoints (e.g., a sender/source and receiver/sink of a data packet) can be determined by aggregating the frequency offsets of the points along the route between them. This capability is not built into regular Ethernet switches, common in enterprise networks.
Current solutions for clock synchronization typically require special hardware that may not be available in many legacy networks. For example, one approach that may be utilized to propagate a synchronized clock over an Ethernet network is to utilize Synchronous Ethernet, also referred to as SyncE, which is an ITU-T standard for computer networking that facilitates the transference of clock signals end-to-end over the Ethernet physical layer. Typically, each Ethernet port of a switch uses its own clock. The SyncE mechanism enables a port of Ethernet switch to use the clock of another port in the same switch. Thus, a network that supports SyncE can enable all link segments along a path to use the exact same clock frequency, i.e. keep synchronization between the two ends with zero frequency offset. However, typical switches in enterprise environments lack the capability to implement SyncE, thus this solution can require replacing hardware in many cases.
Another approach that may be used to propagate a synchronized clock over an Ethernet network is to transmit using the Precision Time Protocol (PTP), which is a protocol used to synchronize clocks throughout a computer network. On a local area network, this approach can achieve clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems. One widely used standard for PTP is the IEEE 1588v2 standard. To achieve high clock accuracy between end-nodes, the IEEE 1588v2 standard offers the “Transparent Clock” time-stamping mechanism, which mandates each switch measure and report the residence-time of a packet in that switch. However, this standard assumes a symmetric network, which requires an Ethernet network to use the same path for both transmission directions. Additionally, the support for the “Transparent Clock” time-stamping mechanism, which is typically needed to achieve sufficiently high accuracy, is not typically provided in switches used in many existing enterprise networks.
Thus, there is a need for a way to enable an HDBaseT® network that utilizes common enterprise Ethernet switches to implement clock synchronization over the Ethernet network in a way that does not rely on specialized hardware in the switches (e.g., hardware with a transparent clock).